[PATCH] D63459: Loop Cache Analysis

[Ettore Tiotto via Phabricator via llvm-commits]

etiotto added a comment.

In D63459#1549307 <https://reviews.llvm.org/D63459#1549307>, @Meinersbur wrote:

> How would a pass use this analysis? It computes a cost for the current IR, but there is nothing to compare it to unless the transformation pass emits the transformed loop nest next to the original pass such that the LoopCacheAnalysis can compute its cost.


The result of the analysis will be a vector of costs for each loop in a loop nest. The cost associated with a loop estimates the number of cache line used if the loop was placed in the innermost position in the nest. Therefore sorting the cost vector in descending order correspond to minimizing the number of data cache misses in the nest. For example loop distribution can use the sorted vector and work out a set of permutation moves (assuming legality constraint are satisfied) to maximize cache locality.


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